HIRANUMA APPLICATION DATA

Karl Fischer Titrator

Watercontents

Data No.

KF2Jun.6.
2017Alcohols

1. Abstract
Water content of Alcohols is determined by Karl Fischer coulometric titrator. In coulometric titration, iodineof Karl Fischer reagent is generated by electrolysis and generated iodine quantitatively reacts with water.
Reaction formula is described below.
H2O ＋ I2 ＋ SO2 ＋ 3RN ＋ CH3OH → 2RN・HI ＋ RN・HSO4CH32RN・HI → I2 ＋ 2RN ＋ 2H＋ ＋ 2e－Alcohols do not interfere the Karl Fischer reaction and direct injection method could apply. Anode solution is
selected in accordance with sample solubility. General-use anode solution contains methanol as solvent.
Alcohols with long carbon chain have low solubility in methanol. In that case, use of anode solution for oil isappropriate.
When fritless cell is used, cathode solution is not necessary.

2. Apparatus and Reagents(1) Apparatus
Titrator：

Karl Fischer Coulometric titrator

Electrolytic cell：Standard Cell

AQ-2200A

Fritless Cell
(2) Reagents
Anode solution：

Hydranal coulomat AG (for general use, nonhalogenated)

Cathode solution：

Hydranal coulomat CG

3. Procedure(1) Fill 100 mL of anode solution and one ampoule of cathode solution into the electrolytic cell as shownin Fig.3.1.
(2) Start blanking to attain stable background.
(3) Wash the syringe with sample.
(4) Draw the sample into syringe and then weigh the syringe.
(5) Inject sample from rubber septum of electrolytic cell as shown in Fig.3.2.
(6) Start titration. Measurement parameter is shown in Table 4.1.
(7) Weigh the syringe again and then set the difference of weight to sample size.

Cathode solution

Anode solution

Fig.3.1. Preparation of the reagents.
Note(1) Do not touch the tip of needle toanode solution.
(2) When injecting, set the tip ofneedle as below figure.

(3) Before pulling out the needle,
draw alittleairdripping of sample.

Fig.3.2. Injection of sample.

4. Parameters and results
Table 4.1. Parameters
Condition File
Cal ModeInterval Time
Current
S.Timer
Blank Value
Unit Mode
Auto Interval
Minimum Count
Back Ground
Sample Size Input
Cell Type

0:Sample weight (net)
X=(H2O-BLANK)/SIZE
20SLOW00
AUTO05ON
Every Time
Standard / Fritlesssec
minug
gug

topreventTable 4.2. Results of water content measurement in alcohols
SampleSize (g)water(μg)

WatercontentAG
CG

0.59880.88900.8710

672.9
991.6
973.6

1124 ppm
1115
1118

Fritless

AG

Standard

AGCG

0.94150.89640.87391.50781.60151.65741047.4
996.7
972.3
138.9
145.7
152.6

1112 ppm
1112
1113
92.1 ppm
91.0
92.1

Fritless

AG

Standard

AGCG

1.5623
1.5496
1.58320.86583
1.368650.83448

142.7
139.4
142.9
156.4
243.5
150.1

91.3 ppm
90.0
90.3
180.6 ppm
177.9
179.9

Fritless

AGStandardAGCG

1.05740.95761
1.027810.87698
0.920310.81105

188.2
172.1
185.3
132.1
138.0
124.0

178.0 ppm
179.7
180.3
150.6 ppm
149.9
152.9

Fritless

AG0.805100.85949
0.97448

122.9
131.1
148.7

152.7 ppm
152.5
152.6

SampleApparatus

Cell

Reagent

Methanol

AQ

Standard

2-propanol

2-methoxyethanoln-hexylalcohol

AQ

AQ

AQ

5. Note(1) Use dried syringe and syringe vial in Fig.5.1, for preventive of contamination by atmospheric water.
(2) Put appropriate anode solution in use according to the solubility of the sample. For example, Hydranal
Coulomat AG-H and Oil are suitable for oils.
Note : these reagents does not correspond to Fritless cell.

Fig.5.1. Draw the sample from syringe vial.